3D association of ER, PR and Her2 at protein levels to aid sub-grouping of breast cancer patients in routine clinical practice

Treatments of patients with solid tumors frequently rely on the relative and semi-quantitative assessment of tissue protein biomarkers by immunohistochemistry (IHC). The perspective of transition to absolute and quantitative assessment of tissue biomarkers is hindered by lack of a suitable method, especially for Formalin Fixed Paraffin Embedded (FFPE) tissues. In this study, we explored the feasibility of Quantitative Dot Blot (QDB) method as a universal platform to quantitate tissue biomarkers as absolute and continuous variables in FFPE samples by measuring unprecedentedly the protein levels of Estrogen Receptor (ER), Progesterone Receptor (PR), Her2 and Ki67 simultaneously in 1048 FFPE samples. When using measured Her2, ER and PR levels as coordinates to develop 3D scatterplot, we observed a distinct distribution pattern of the samples with natural segregation of three groups as the likely phenotypical projection of known intrinsic subtypes. Thus, we have achieved a major milestone in this transition by identifying the first practice method for daily clinical practice, and one clinical usage in 3D subtyping of samples for prediction and prognosis. This study may serve as basis for a new field of Quantitative Diagnosis where diagnosis, prognosis and prediction are derived from database analysis of protein biomarkers as absolute and continuous variables.